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Background: Carbon 13-labeled magnetic resonance spectroscopy (13C-MRS) with [1-13C]-glucose administration, the 13C atom that behaves as a radio inacti ve tracer in the brain, can differentiate aerobic and anaerobic glucose metabolism by detecting [4-13C]-glutamate (Glu C4) and [3-13C]-lactat e (Lac C3). Objective: To investigate the cerebral metabolic derangement resulti ng from mitochondrial dysfunction in mitochondrial myopathy, encephalopathy, lac tic acidosis, and strokelike episodes (MELAS). Design: Application of a new 13C -MRS technique to a patient with MELAS compared with control subjects (n=7). Pa tient: A 19-year-old woman with an A3243G mitochondrial mutation who underwent 13C-MRS for 30 minutes after oral administration of [1-13C]-glucose (0.75 g/ kg). Result: Decreased Glu C4-labeling (P < .001) and increased Lac C3 synthesi s (> 2 SDs) compared with controls were demonstrated in the patient with MELAS. Conclusion: This first report on 13C-MRS observation of cerebral glucose metabo lism in a patient with MELAS demonstrated the presence of low glutamate producti on via the tricarboxylic acid cycle compared with high lactate synthesis by glyc olysis. The present findings suggest that the clinical use of 13C-MRS can be ex tended to diagnose mitochondrial dysfunction and monitor cerebral glucose metabo lism in a variety of mitochondrial disorders.
Background: Carbon 13-labeled magnetic resonance spectroscopy (13C-MRS) with [1-13C] -glucose administration, the 13C atom that behaves as a radio inacti ve tracer in the brain, can differentiate aerobic and anaerobic glucose metabolism by detecting [4 -13C] -glutamate (Glu C4) and [3-13C] -lactat e (Lac C3). Objective: To investigate the cerebral metabolic derangement resulti ng from mitochondrial dysfunction in mitochondrial myopathy, encephalopathy, lac tic acidosis, and strokelike episodes MELAS) with a new 13C-MRS technique to a patient with MELAS compared with control subjects (n = 7). Pa tient: A 19-year-old woman with an A3243G mitochondrial mutation who underwent 13C-MRS for 30 minutes after oral administration of [1-13C] -glucose (0.75 g / kg). Results: Decreased Glu C4-labeling (P <.001) and increased Lac C3 synthesi s (> 2 SDs) compared with controls were demonstrated in the patient with MELAS. Conclusion: This first report on 13C-MRS observation of cerebral gl ucose metabo lism in a patient with MELAS demonstrated the presence of low glutamate producti on via the tricarboxylic acid cycle compared with high lactate synthesis by glyc olysis. The present findings suggest that the clinical use of 13C-MRS can be ex tended to diagnose mitochondrial dysfunction and monitor cerebral glucose metabo lism in a variety of mitochondrial disorders.